The present invention is in the field of information processing systems, and more particularly is directed to information storage devices for such systems.
The development of information processing systems has resulted in the development of associated data storge, or memory, subsystems. As the complexity and size of modern data bases and computer systems has increased, there has generally been a correspondingly growing requirement for higher speed and increased capacity on-line mass memories.
The density of memory elements (or storage cells) in memory systems has become an increasingly significant factor in meeting these growing requirements. Representative devices which are currently used for high density, relatively fast, on-line mass memories are the CDC large disk (having 300K bits/in.sup.2), the IBM 3850/B4 (having 328K bits/in.sup.2), and the Ampex Terabit memory (having 450K bits/in.sup.2). All of these systems provide read/write times on the order of 0.1 to 1.0 microseconds. In addition, semiconductor, CCD, magnetic bubble, video disk and Josephson junction memories are presently being developed to provide storage densities as high as 860 megabits per square inch, with read/write times as low as 10 picoseconds. Furthermore, electron beam addressable memories are presently being considered with design goal densities on the order of 10.sup.10 -10.sup.12 bits/in.sup.2, with 10 nanosecond read/write times.
Although the existing prior art devices, as well as those presently being developed, do provide relatively compact, large capacity, high speed on-line memories, these characteristics are, of course, limited.
It is an object of the present invention to provide an improved compact, high speed mass memory.